Standard earth drill rigs of the type manufactured and sold by Central Mine Equipment Company, among others, have been provided with an upright drill frame that pivots from a horizontal traveling position to a vertical drilling position. In those standard machines made heretofore, a drive train is connected between a right angle drive and a kelly bar by a flexible chain coupling, as illustrated in Fehrmann and Rassieur, U.S. Pat. No. 3,309,898. In these machines, somewhat diagramatically illustrated in FIGS. 5 and 6 of the accompanying drawing, when the drill is in a vertical position, the bottom of the kelly bar is just above the right angle drive vertical output shaft and below the pivot access of the drill frame. As indicated in FIG. 5, as the upright assembly is rotated from a horizontal to a vertical position or vice versa, the lower end of the kelly bar swings out away from the drill. This standard design does not allow for a connection between the output shaft and the kelly bar that will function at positions intermediate the horizontal and the vertical. In fact, in order to permit the drill frame to be swung to the horizontal position, the flexible chain coupling has to be raised on the kelly bar until it clears the vertical drive shaft.
One of the objects of this invention is to provide a drill rig in which the drill frame can be swung from vertical to horizontal without having to uncouple the vertical drive shaft from the kelly bar.
Another object is to provide such a drill rig in which the kelly bar, hence the rotary table, can be driven through any angle of the drill frame from substantially horizontal to vertical, to permit angled drilling.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.